Dr. Earl Garnet, St. Paul Hospital's ER chief, is accused of a tragic oversight after a nurse, initially complaining of flulike symptoms, mysteriously dies while under his care. Garnet suspects the cause is a ""superbug,"" a lethal mix of Legionella and staph, resistant to antibiotics. Panic sets in as the number of cases rises, and soon the hospital is placed under quarantine and overrun by police, the media and the National Guard, which leaves Garnet little time to search for a common link among the victims. However, Garnet's wife, an obstetrician at nearby University Hospital, has a hunch that the deaths may be the work of ""The Phantom,"" someone rumored to deliberately infect hospital employees known for their unkind treatment of patients. Clement's (Lethal Practice) own background as a physician comes across in his use of technical terminology and ability to capture hospital politics, which adds to the terror. (Mar.)